Conventional tillage implements such as the disk harrow, disk cultivator and rotating hoe are not entirely suitable for preparing ground for seeding where established grass sod is present. In order to provide a tillage apparatus better suited for preparing ground for seeding or grassland renovation where sod is present, towed implements having a series of cutting wheels driven to open a furrow have been developed. Devices of this type are shown, for example, in U.S. Pat. Nos. 4,023,510; 4,043,281; 4,043,404 and 4,051,792. This type of tillage implement is particularly useful where legumes are to be grown in established grass sod, especially since the ground surface is often uneven or rocky and may have grass swards of differing thickness thereon. The implement is also useful for interseeding grasses such as rye and wheat into Bermuda grass.
Cutting of the sward and sod mat and provision of a furrow therein has been a continuing problem. Various types of cutter wheels, such as those disclosed in U.S. Pat. No. 4,043,404, have been devised. In areas where stringy materials, especially Bermuda grass or hay are present, wrapping of the cutter wheel can occur frequently. The materials can become caught in the teeth, in the hooked-shaped sections, or in the deep gullets of the wheel and become wrapped around the wheel and the shaft hampering the effectiveness of the tillage apparatus. The operator must then leave his tractor to remove the build-up. Untangling of the material is very time-consuming and difficult.
Typical of previous wheels which are only effective when rotated in one direction, care must be taken to correctly mount them on the drive shafts so the teeth are properly oriented with respect to the direction of rotation. A wheel is ineffective for cutting a furrow if mounted on the shaft with the teeth facing in the wrong direction.